Jobseekers meet potential employers recruiting during the Women Job Fairs in New York, on Oct. 21. Since the recession's end in June 2009 in the United States, immigrants have seen job growth but native-born workers have continued to lose jobs.

• In the year following the official end of the Great Recession in June 2009, foreign-born workers posted a net gain of 656,000 jobs, while native-born workers lost 1.2 million. The foreign-born category includes legal and illegal immigrants.

• As a result of immigrants' recent job gains, the unemployment rate for immigrant workers fell during this period from 9.3 percent to 8.7 percent, while for native-born workers it rose from 9.2 percent to 9.7 percent. For both groups, unemployment remains far above where it stood before the recession.

• Although immigrants have been finding employment, the poor job-market conditions have pushed average wages down. Median weekly earnings of foreign-born workers fell 4.5 percent from mid-2009 to mid-2010, compared with a decline of less than 1 percent for native-born workers.

"It might be that ... immigrants were more accepting of lower wages and reduced hours because many, especially unauthorized immigrants, are not eligible for unemployment benefits," Pew center researcher Rakesh Kochhar writes, along with co-authors of the study.

Immigrants appear to be more avid in pursuit of jobs: In the year since the recession officially ended, the share of working-age immigrants who either have jobs or are looking for work edged up from 68 percent (of all immigrants) to 68.2 percent. By contrast, native-born Americans have been dropping out of the labor force, with the participation rate falling from 65.3 percent in the middle of 2009 to 64.5 percent a year later.

The report, drawing on Census and Labor Department data, raises anew questions that are particularly sensitive because of the weak economy: Are immigrants (including many in the country illegally) reducing employment opportunities for native-born Americans? And are immigrants pushing down wage levels?

In public opinion polls, Americans express ambivalence. They strongly favor tighter curbs on illegal immigration, yet in a May Associated Press/Univision survey 62 percent agreed with the statement "Illegal immigrants take jobs that Americans don't want."

Some economists caution against the view that immigrants detract from opportunities for native-born Americans.

"Data show that, on net, immigrants expand the U.S. economy’s productive capacity," he writes in an August report for the Federal Reserve Bank of San Francisco. He found "no evidence that these effects take place at the expense of jobs for workers born in the United States."

Still, many economists say that more immigrants in the labor force mean tougher times for native-born workers at the bottom end of the labor market, who are younger or less-skilled.

The story of the past decade is similar to that of the past year, he says: Immigrant employment has generally increased, while the overall job market failed to add jobs for native-born Americans. (What researchers can't say for sure is how the job market for native-born Americans would have fared with less immigration.)

Many illegal immigrants left the US during the recession, as jobs in construction and other industries dried up. Now, Mr. Camarota says, that exodus has stopped. And the Pew center concludes that "the economic recovery may be attracting immigrant workers back into the U.S."